Please find the objective below that most closely matches your requirements for "syncing multiple accounts":
Objective: Add Contacts from multiple Google accounts to my iPhone, but with the contacts from each Google account kept separate
- In this situation, I would suggest syncing your primary Google account with iPhone using this app. Add any additional Google accounts by going to your iPhone Settings > Passwords & Accounts > Add Account > Google.
- Only the account you sync with the app will have groups, as iOS does not pull in groups from Google accounts configured in iPhone Settings.
Objective: Create a 3-way Sync between 2 Google accounts and an iPhone account, with the same contacts in all 3 places
To create a 3-way sync, I would suggest syncing your primary Google account with iPhone using this app, and your secondary Google account using this app's sister product ("Contacts Sync for Google Gmail" or "Synctastic")
Alternatively, if you have multiple iOS devices such an iPhone and iPad, you can install this app on each of your devices at no additional charge, and sync your primary Google account with iCloud from your primary iOS device, and your 2nd Google account with iCloud from your other device.
Alternatively, you can toggle between Google accounts by going to Contacts Sync > Accounts, and then sync each one individually. This will also create a 3-way sync
Download Contacts Sync for Google Gmail: https://itunes.apple.com/us/app/contacts-sync-for-google-gmail/id454390333?mt=8
Download Synctastic for Google: https://itunes.apple.com/us/app/synctastic-for-google-sync/id686378579?mt=8
Objective: Directly transfer contacts from one Google to another Google account
To accomplish that, please follow these instructions:
- Go to your iPhone Settings > Passwords & Accounts, and add the source Google account if it's not already there, with Contacts enabled.
- Go to Contacts Sync > Accounts, and sign into your destination Google account.
- Go to Contacts Sync > Accounts > iPhone Account to Sync, and choose the source Google account you configured in step 1
- Go to Contacts Sync > Sync, and sync your contacts in the desired direction